I find programming model in WebOS very intuitive and easy. I really like it and even though I have no real device to test anything, there is an emulator and I think is very complete (probably better than the first iPhone Simulator app)

These are some notes on how to create Palm Pre apps using Terminal in the Mac but this should not be different in any other Unix like OS.
There is a Eclipse Plugin that should make things easier but I don't like very much Eclipse, is kind of sluggish, I prefer Xcode or NetBeans but there are no Web OS Development official plugins for these IDEs now. So my best choice is Terminal + Coda (Coda is awesome!!).
Moreover, Coda has Terminal inside of it so no need to really open Terminal.app in the Mac.